Effective management of food and agricultural waste faces a crucial challenge in today’s world, primarily due to the necessity to sustainably feed the ever-growing global population. A significant portion of this waste generated is plant waste, including both sugar-rich and starch-rich materials. These waste materials are often considered as non-product leftovers due to their perceived lack of economic value compared to the costs associated with their collection, storage, and recovery for reuse. However, by employing appropriate technological methods, such wastes can be utilized as feedstocks for the production of value-added products such as polyhydroxyalkanoates (PHA). PHAs are biodegradable polymers with a wide range of applications, offering an environmentally friendly potential substitute to the conventional plastics. Recycling plant wastes holds immense potential for application across various industries, ultimately leading to a reduction in the adverse impacts caused by their accumulation in the environment. This chapter delves into the utilization of plant wastes (sugar-rich and starch-rich wastes including beet molasses, sugarcane molasses, corn steep liquor, and starchy wastewater) for the production of PHAs. It discusses PHA recovery methods and characterization techniques crucial for evaluating the properties of PHA, thereby laying the groundwork for understanding the material quality and suitability for various applications. Additionally, diverse applications of PHAs, ranging from packaging materials to biomedical devices, are explored by highlighting the potential of utilizing plant wastes to contribute to a circular economy.